Metal oxide phosphor microparticle and process for producing the same; utilizing the same, dispersion liquid, fluorescence conversion membrane, method of separating metal oxide phosphor microparticle, fluorescent liquid, fluorescent paste, phosphor and process for producing the same; and fluorescence converter

A dispersion of metal oxide-based phosphor microfine particles comprising:

• (a) a dispersing medium containing an organic compound having one or more functional groups bonded to a terminal end or a side chain thereof, and
• (b) the metal oxide-based phosphor microfine particles comprising a matrix crystal made of a metal oxide and a metal element doped as an emission center into the matrix crystal, wherein said microfine particles are provided with an organic group coordinated to a surface thereof which is formed by dissociating at least one of the functional groups from the organic compound.

A method of separating metal oxide-based phosphor microfine particles comprising:

• subjecting a mixture of the metal oxide-based phosphor microfine particles and a solvent to centrifugal separation, filtration, natural sedimentation or combination thereof for classifying the microfine particles to separate transparent metal oxide-based phosphor microfine particles containing the solvent from the mixture.

A method of separating metal oxide-based phosphor microfine particles comprising:

• mixing a mixture of the metal oxide-based phosphor microfine particles and a solvent, with a solvent capable of varying a dispersing condition of the microfine particles, and
• subjecting the resultant mixture to centrifugal separation, filtration, natural sedimentation or combination thereof for classifying the microfine particles to separate transparent metal oxide-based phosphor microfine particles containing the solvent from the mixture.